A building block has opposing like outer members spaced apart by at least two risers as cross members inward from outer member ends leaving a center open with a void between the outer members and the risers. The risers extend from the bottom of the block to above the outer member tops. A continuous tongue projects upward from the top of the outer members parallel thereto along the length of the outer member and mates with grooves along the bottom of a similar outer member stackable thereon for ease of block alignment. A next stacked block is nailed to the risers projecting into its center.

A wall comprises building blocks with opposing like outer members spaced apart by at least two risers as cross members inward from outer member ends leaving a center open with a void between the outer members and the risers. The risers extend from the bottom of the block to above the outer member tops. A continuous tongue projects upward from the top of the outer members parallel thereto along the length of the outer member and mates with grooves along the bottom of a similar outer member stackable thereon for ease of block alignment. A next stacked block is nailed to the risers projecting into its center.

Construction systems and methods of the invention provide building constructions systems which may be assembled, such as for example, by stacking and interconnecting standardized modular blocks between standardized modular posts. The modular posts may be comprised of a sleeve of WPC or other composite material surrounding a reinforced concrete core. The blocks, posts and other components in accordance with the principles of the invention may have a variety of geometries and features. These components may together form the basis of a modular, standardized method and system of constructing dwellings or other buildings.